1. The Field of the Invention
This invention relates to drag reduction devices and, more particularly, to novel apparatus for reducing drag over a flow surface and methods for using same.
2. The Background Art
It has long been desirable to reduce the resistance force which acts against a body (e.g., airplane, watercraft, automobile, airfoil, or the like) moving through a fluid (e.g., liquid or gas) parallel and opposite to the direction of motion. Correspondingly, drag reduction apparatus and methods have been developed by those skilled in the art to assist in reducing the drag coefficient which acts against a moving body.
For example, those skilled in the art developed drag reduction articles comprising a conformable sheet material having a first surface including a series of parallel peaks separated from one another by a series of parallel valleys, whereas all of the peaks are dimensionally identical to each other as are all of the valleys. In addition, an earlier patent of the present inventor, U.S. Pat. No. 5,485,801, is directed to a mechanically altering flow control surface which is capable of improving the hydrodynamic flow of water across the exterior surface of a watercraft while further providing a means for shielding the keel and/or bow of the watercraft from abrasive damage.
Watercraft such as, for example, motorboats, jet skis, wave runners, yachts, sailboats, kayaks and canoes are generally formed of a fiberglass composite material which can become easily damaged or seriously scratched as a result of forcible impact or collision with sand, gravel, rocks or other obscure objects or debris found in water. Typically, when a watercraft is beached, removed from and/or launched into water, or while the watercraft is merely moving through the water, the lowermost portion of the hull of the watercraft (generally encompassing portions of the stem, bow, forefoot, keel and stern) is particularly susceptible to abrasion. Consequently, abrasive damage usually promotes corrosion and structural weakening of the hull of the watercraft. In addition, the bow of a watercraft may procure serious damage as a result of forcible contact with the docking platform where the watercraft is secured.
Traditionally, the keel and bow (inclusive of the stem and forefoot) of a watercraft are generally formed having a substantially arcuate shape which structurally encourages the hydrodynamic flow of water across the exterior surface of the hull as the watercraft moves through water. The hydrodynamic performance of a watercraft, however, can be sufficiently reduced as a result of abrasions on the keel and/or bow of the watercraft. In this regard, serious damage such as, for example, deep scratches, penetration, or abrasions in the exterior surface of the hull of a watercraft, may generate substantial dragging or suction forces which generally act against the motion of the immersed watercraft and, more importantly, may significantly affect the overall hydrodynamic performance of the watercraft in water. Moreover, abrasions in the hull of a watercraft, particularly formed of fiberglass, will generally necessitate the repair and/or replacement of the hull and those structural features of the body of the watercraft functionally affected.
The repair and/or replacement of the hull of a watercraft is customarily costly, and typically sorely inconvenient to the owner. Accordingly, the capacity for protecting the keel and/or bow of a watercraft from abrasive wear and tear, damage, and/or deep scratching has encouraged significant concentration and development within the marine industry as to the various options available for protecting the hull of a watercraft and reducing the cost of repair and maintenance of the exterior surface thereof, while substantially preserving the inherent monetary value of the watercraft itself.
In an attempt to structurally accommodate the ability to protect at least a portion of the lowermost portion of a watercraft from structural damage caused by abrasion and deep scratching, those skilled in the art developed prior art bow protectors. A serious disadvantage associated with bow protectors of the prior art, however, is their general inability to adequately conform over the keel or bow of the particularly engineered keel or bow configuration or design of a specific make or model of watercraft.
Prior art bow protectors are traditionally designed and manufactured as a preformed unit having a substantially rigid "V" shaped configuration. The material comprising prior art bow protectors is usually only slightly deformable or conformable when disposed over the particular configuration of the bow or keel of a watercraft. In this regard, since the design and configuration of the hull of a watercraft is not universal in relation to other watercraft, prior art bow protectors are typically unable to provide sufficient universal conformity over the keel and/or bow of watercraft having various sizes, shapes, and/or configurations.
Similarly, because the manufacturing of prior art bow protectors in various sizes and shapes for conformity in relation to different makes and models of watercraft can be economically impractical, bow protectors of the prior art are typically molded or preformed in several conventional sizes and shapes in an attempt to provide an approximate conformity over the dimensional size and configuration of the keel and/or bow of the various watercrafts.
Other practical disadvantages with bow protectors of the prior art have also emerged in relation to the installation of bow protectors over the keel and/or bow of the watercraft. For example, in order to properly install prior art bow protectors over a nonconforming keel and/or bow of a watercraft, at least two skilled installers are typically required who generally apply compression forces against the preformed body of the prior art bottom protector in order to bend and slightly alter the shape of the bow protector to minimally conform over the keel and/or bow of the watercraft. In this regard, prior art bow protectors are generally installed by two or more skilled technicians having received special training in the installation process and utilizing the necessary tools to minimize the plurality of problems which may arise during the installation process.
Similarly, there are significant disadvantages associated with the reduction of the overall hydrodynamic performance of a watercraft as a result of installation of nonconforming prior art bow protectors over the keel and/or bow of the watercraft. For example, several bow protectors of the prior art are generally formed having a substantially empty chamber (e.g., defined by an epoxy adhesive and spacer blocks) formed between the keel and/or bow of the watercraft and the internal surface of the prior art bow protector. This empty chamber essentially modifies the distinctively engineered configuration or design of the original keel and/or bow of the watercraft, thus producing meaningful resistive forces or drag coefficient. In particular, the modification of the designed shape, conformation, and/or configuration of the keel and/or bow of a watercraft may seriously affect the overall efficiency of the hydrodynamic flow of water across the exterior surface of the watercraft.
In addition to the foregoing disadvantages, prior art bow protectors typically promote hydrodynamic dragging or resistance as a result of suction forces acting against the exterior surface of the keel and/or bow of the watercraft. Since boat protectors may be secured to the exterior surface of the watercraft by means of an epoxy adhesive and spacer blocks to form a hollow chamber, when prior art bow protectors are not substantially conformed over the configuration of the keel and/or bow of the watercraft, the force of the water resistance acting against the keel and/or bow of the watercraft as it moves through the water typically overwhelms the means for securing the bow protector in relation to the keel and/or bow of the watercraft. In this regard, prior art bow protectors usually become detached from the exterior surface of the watercraft and, correspondingly, have a direct effect on seriously reducing or inhibiting the expected hydrodynamic performance of the watercraft.
Furthermore, bow protectors of the prior art may be formed of a clear plastic material comprising a molecular composition which can be sufficiently degraded as a result of persistent contact with ultraviolet light. As appreciated by those skilled in the art, ultraviolet light typically breaks down or alters the chemical structure of these types of clear plastic materials which generally results in the discoloration of the plastic so as to display a slightly yellowish tint. Moreover, long exposure to ultraviolet light may cause the clear plastic of prior art bow protectors to separate from the exterior surface of the watercraft as a result of a chemical breakdown of the characteristics of the adhesive applied to the backing of prior art bow protectors for the purpose of securing the cover member to the keel and/or bow of the watercraft.